The ladder style of construction of rucksack harness adjustment systems is well known. One known system is the PARALUX (Trade Mark) suspension system. Many modifications and variations of this system are currently available on the high grade rucksack and climbing equipment market. The PARALUX™ system is known for its ruggedness, durability and stability in use. Some modifications of this system have similar performance to the PARALUX™ system but usually comprise expensive alternative components.
In the PARALUX™ suspension system a plurality of transverse webs are sewn in ladder-like fashion to the back wall of the rucksack. The shoulder straps terminate in a strap which is threaded through a selected one of the webs depending on the desired location of the shoulder straps. The strap is then threaded through a buckle and tightened, threaded under the next highest ladder web, through a web on the shoulder harness, and then threaded through a further ladder web. The loose end of the strap is pushed down behind the ladder configuration. Finally, a top stabilizer web is threaded through buckles at the top of the ladder to stabilize the connection.
A known disadvantage of the ladder type adjustment system is its relative complexity. A rucksack owner may easily forget how to adjust the system to account for different loads or different users. Additionally, at points of sale, adjustment of a rucksack to fit a number of customers is time consuming and off-putting to both the customer and retailer.
German Gebrauchsmuster No. G 92 11 744.9 discloses a rucksack comprising a backpack having at an upper region of the back wall two carrier straps, which are height-adjustably secured to the back wall. A plurality of transverse loops or webs are stitched to the back wall of the backpack in spaced apart and ladder-like fashion. The shoulder straps are joined together by a yoke, and a plate attached to the yoke is inserted behind a selected loop and is locked in position by means of a snap fastener.
German Patent Application No. DE 3045881 discloses a height-adjustable system for attaching a carrying harness to a rucksack in which a number of transverse bands or webs are sewn to the rear wall of the rucksack to form a ladder-like construction similar to the PARALUX™ system described above. The transverse bands are sewn to the rear wall by means of stitches which extend in a v-shape, to provide for varying shoulder widths.
International Patent Application No. PCT/IE94/00027 describes an alternative adjustment system, known as the APS™. This system comprises a pair of shoulder straps connected together at a yoke. The rear wall of the rucksack is provided with a plurality of overlapping slats, which define a plurality of open-ended pockets or sleeves. The user selects a pocket corresponding to the desired location of the shoulder straps. The yoke is then held in position in the chosen pocket by a tie strap, which is fastened to a buckle located below the series of pockets.
All of the above systems suffer from a common disadvantage, that is, the level of adjustment available to the user is limited by the number and spacing of the webs, loops or pockets provided on the rear wall of the rucksack. Each of the systems provides a varying degree of adjustment, but in each case the shoulder straps may only be located at a finite number of discrete locations on the back of the rucksack, which may result in a level of discomfort for some users.
Mechanical means are known for adjusting the height of the shoulder harness on rucksacks, typically in which the yoke connecting the shoulder harness slides in vertically arranged runners or tracks on the back wall of the rucksack, and is locked in place by a locking system. Known mechanical systems include the TORSO TRAC™ suspension system (U.S. Pat. No. 4,860,936), and the systems described, for example, in European Patent 0,173,024 and German Gebrauchsmuster No. G 87 16 869.3. While these mechanical systems offer a quick and easy method of height adjustment they are expensive to manufacture. Also there is a tendency for the yoke to slip and the locking system can cause problems.